Study On The Influence Of Internal Maintenance On Performance Of High Performance Road Concrete

With the development of China’s economy and the increasing overload phenomenon,the application of high-performance concrete in the construction of highways and bridges in China is becoming more and more common.High-performance concrete has higher strength and better durability,but it is also more prone to self-shrinkage cracks and affects service life.The addition of super absorbent Polymer(SAP)to the internal curing of concrete is one of the common methods for reducing self-shrinkage cracks.In this paper,we will study the effect of curing in SAP on the self-shrinkage of cement mortar,and also study the effects of curing in SAP on the mechanical properties of concrete,such as mechanical strength,wear resistance,salt resistance and chloride ion permeability.Including the following points:(1)By testing the water absorption ratio of SAP in an alkaline salt solution,the actual water absorption capacity of SAP in the cement slurry is simulated,and a reasonable additional water diversion ratio is established;the water release performance of the selected SAP is tested,and the degree of hydration is passed.Experiment to study the internal maintenance effect of SAP.(2)The effects of SAP dosage and additional water diversion on the mechanical strength of high performance concrete were studied by a large number of experimental systems.The experimental results show that SAP can significantly reduce the early strength of concrete and have a certain negative impact on the 28 d strength.However,when the SAP content and the additional water diversion multiple are small,the strength of concrete 28 d can be improved.The amount of fly ash in SAP is studied.The effect on concrete strength,when the amount of fly ash is 10% and 15%,is favorable for the late strength of concrete.(3)By testing the effects of different SAP dosages and additional water diversion times on the self-shrinkage of cement mortar,experiments show that SAP can significantly improve the self-shrinkage of cement mortar,and the maximum shrinkage is 51.5%.Through the simulation of 120 d contraction experimental data of cement mortar,seven common models were compared by SPSS software,and a concise equation was obtained to predict the self-shrinkage change of cement mortar under internal curing.The calculated and experimental values of the equation The degree of fit is good.(4)The effects of curing in SAP on the durability of concrete were evaluated by salt freeze,chloride ion permeability and wear resistance.The concrete peeling rate,dynamic elastic modulus,compressive strength loss and flexural strength were measured before and after salt freezing.The loss amount and other indicators were used to study the effect of SAP on the salt resistance of concrete;the influence of SAP on the chloride ion permeability and wear resistance of concrete was studied by electric flux and wear per unit area.Experiments have shown that a reasonable amount of SAP can improve the durability of concrete.